"I never used the word ban. However I will look very closely at specific derivative products like CDS on sovereign debts and the speculative risks attached to them," Barnier said.

"I want to add transparency, light, control. We need to understand who is doing what", he said.

Greece repeatedly accused speculators in the derivatives market of pushing the country towards the brink by placing "naked" CDS bets – where investors do not own the underlying bond – that the government will default on its debt.

Barnier, who was on his second visit to London in a month, said he heard Prime Minister Gordon Brown's and Chancellor Alistair Darling's requests to have more time to negotiate a European directive to regulate hedge funds and private equity.

"I'm going to help find a good agreement in June so we achieve a positive result on hedge fund and private equity regulations, one that's intelligent and effective," he said.